in the related arts, a technology is known by which reception electric field strength that is corrected depending on characteristic change due to variation of temperature and variation of power-supply voltage is detected in a mobile wireless communication device (for example, see Japanese Laid-open Patent Publication No, 7-35809).
In recent years, a mobile communication system using orthogonal frequency division multiple access (OFDMA) having high spectrum efficiency has been put to practical use in order to cope with an increase in a data amount of wireless communication. For example, as a mobile phone system, standards of Long Term Evolution (LTE) have been developed in 3rd generation partnership project (3GPP).
In LTE, OFDMA is used in a downlink that corresponds to communication from a base station to a wireless terminal, in addition, single carrier-frequency division multiple access (SC-FDMA) is used in an uplink that corresponds to communication from a wireless terminal to a base station.
In LTE, when a plurality of base stations exists, handover is used by which a wireless terminal is coupled to an optimal base station. The wireless terminal periodically detects a neighboring cell (cell is the area in which communication with a base station is allowed to be performed) while communicating with a base station to which the wireless terminal is being coupled and reports reception quality of the cell to the base station to which the wireless terminal is being coupled. That procedure is called “Measurement”. The base station that receives the report from the wireless terminal selects an optimal cell from a list of cells and the reception qualities, and executes processing of changing the base station that is a connection destination. That procedure is called “Hand-over”.
As the reception quality that is reported to the base station, for example, there is reference signal reception power (RSRP) and reference signal reception quality (RSRQ). The RSRQ is calculated from the RSRP and a received signal strength indicator (RSSI). The RSRP and the RSSI are measured using a received signal of an OFDM symbol that includes a reference signal (RS) that is transmitted in a downlink.
For example, in a definition of 3GPP, an RSSI is defined as an average value of the total reception power (serving cell, neighboring cell, thermal noise, and the like) that are observed in OFDM symbols that include RSs on the certain number of resource blocks. As a method of measuring such an RSSI, there is a time domain method of measuring an RSSI in a time domain and a frequency domain method of measuring an RSSI in a frequency domain.